1. Cross-Reference to Related Applications
The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2001-020637 filed on Jan. 29, 2001 the entire contents thereof is hereby incorporated by reference.
2. Field of the Invention
The present invention relates to a heating device for an external combustion engine such as a Stirling engine.
3. Description of Background Art
In Stirling engines, an electric heater using a battery as a power source or a burner for burning a fuel has been used as a heating device for heating a heating portion, that is, an expansion chamber of the Stirling engine.
By the way, an electric heater as a heating device is suitable for a relatively small-sized Stirling engine because an energy density of the existing battery used as a power source for the electric heater is in the order of about 50 to 100 wh/kg. However, the electric heater fails to satisfy a long-time operation for the Stirling engine. On the other hand, a burner is suitable for a large-size Stirling engine because it can generate a large quantity of heat. However, the burner is unsuitable for a small-sized Stirling engine in terms of stabilization of combustion in a control state with a small quantity of heat and the property of an exhaust gas.
In view of the foregoing, the present invention has been made, and an object of the present invention is to provide a heating device for an external combustion engine, which is capable of improving stabilization of the combustion in a controlled state with a relatively small quantity of heat and for improving the properties of an exhaust gas. The present invention realizes an increased operation of the external combustion engine.
To achieve the above object, according a first feature of the present invention, there is provided a heating device for an external combustion engine which includes a combustion housing provided for surrounding a heating portion of an external combustion engine. An fuel-air mixer is provided at one end of the combustion housing. An exhaust pipe is provided at the other end of the combustion housing. An oxidation catalyst is disposed in the combustion housing for accelerating combustion of a fuel-air mixture of a fuel and air supplied through the fuel-air mixer. It is to be noted that the external combustion engine and the heating portion correspond to a Stirling engine E and an expansion chamber 11 in an embodiment of the present invention to be described later, respectively.
With this first feature, since the catalyst type heating device is adopted, it is possible to realize continuous combustion in a controlled state with a relatively small quantity of heat, and hence to stably heat the heating portion of the external combustion engine. Further, since continuous combustion by adopting the catalyst type heating device improves the property of the exhaust gas and eliminates the occurrence of combustion oscillation, it is possible to operate the small-sized external engine with comfort for a long time.
According to a second feature of the present invention, in addition to the first feature, the oxidation catalyst is supported by an outer surface of the heating portion disposed in the combustion housing.
With the second feature, since the thermal transfer from the catalyst to the heating portion of the external combustion engine is improved, it is possible to enhance a thermal efficiency and hence to contribute to reduction in fuel consumption.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.